Unity Technologies

Total IAP Revenue contains both Verified and Unverified Revenue. Revenue reported in the dashboard goes through a receipt verification process for iOS App Store and Google Play Store. We take the receipt from the transaction and verify it with Apple or Google servers. So Unverified Revenue is just that; transactions that failed to verify when checking with Apple or Google.

The reason this is less secure is because all of the data is still on the player's device, so they can decompile the app and make any changes they want. But it is easy to implement and does provide some additional security.